The present invention relates, in general, to the storage of liquids and, in particular, to a new and useful system for detecting the overflow of liquid and/or slurry contents from a storage tank.
It is common practice to store liquids and semi-liquids such as slurries in storage tanks. In many cases, these storage tanks continously receive a flow of the liquid and/or slurry which subjects the tanks to possible inflow and outflow inbalances which can result in the liquid and/or slurry overflowing from the tanks. In response to the overflow problem, overflow systems having overflow boxes, pipes or launders are often used in conjunction with the storage tanks to contain the overflow. These overflow systems must be capable of handling any expected overflow rate that is likely to be encountered. However, in many instances, detecting the beginning of an overflow condition is difficult if not impossible due to the size of the overflow boxes and associated piping provided. Normally, the size of these discharge systems prevents the overflow from completely filling the overflow area (unless the rate of overflow is quite large), precluding a positive measurement of the overflow.
Because of the inability to detect and/or measure the size of the overflow, sensors and transmitters have been provided within the tanks at a high tank level in order to indicate an upcoming overflow in the tank. However, these in-tank devices have generally proven to be unreliable due to various factors such as errors in level indication, errors in the alarm systems used, pluggage of the sensors, poor calibration of the devices, and/or changes in liquid/slurry densities, etc. Therefore, it is quite common that a high tank level of liquid and/or slurry may not be indicated or alarmed to an operator prior to an overflow.
Accordingly a need exists for a system for alerting an operator at an early stage of a tank overflow situation by positive detection of the actual overflow.